plasma membrane

Question 1

plasma membrane

Answer 1

• Encloses the contents of the cell.
• Regulates and controls the movement of substances into and out of the cell
• Plasma membrane of organelles have a plasma membrane of similar composition allowing them to fuse for exocytosis and endocytosis.

Question 2

fluid mosaic model

Answer 2

Referred to as the fluid mosaic model because:

• Fluid: as the phospholipid molecules and proteins can move freely or laterally (allowing them to carry out their necessary functions).

-Mosaic: as the membrane consists of many different components (including proteins, cholesterol, carbohydrates and phospholipid molecules).

Question 3

phospholipid molecules

Answer 3

Have a hydrophilic (polar) head (composed of phosphate and glycerol) with a strong affinity for water that will point towards the water.

Have a hydrophobic (non-polar) tail composed of saturated or unsaturated fatty acid) with a weak affinity for water- will point away from water.

Saturated fat and tails have all single carbon bonds and are straight

Unsaturated fatty acids have one or more double carbon bonds and are linked

Question 4

integral proteins

Answer 4

Embedded within the membrane and span part or entire phospholipid bilayer

(known as transmembrane).

Outer hydrophobic region

Inner hydrophilic region

Functions include:

Allow transport of hydrophilic molecules

across the membrane

Act as enzymes and catalyse reactions

Signal transduction

Cell-to-cell recognition

Allow cells to link together and can

anchor to other cells

Question 5

peripheral proteins

Answer 5

Peripheral proteins:

Exist outside or on the edge of

the membrane.

• Temporary
• Not used for transport as they

don’t span the entire membrane

Function as:

• Enzymes
• Receptors
• Structural attachment points
• Cellular recognition sites.